Microwave sterilization or pasteurization

ABSTRACT

Various embodiments of processing systems and components for sterilization or pasteurization and associated methods of operation are described herein. For example, a method of sterilization or pasteurization includes immersing an item in an immersion fluid, and the immersed item is subject to a hydrostatic pressure of the immersion fluid. The method also includes applying microwave energy to the item while the item is immersed in the immersion fluid and subject to the hydrostatic pressure of the immersion fluid. The hydrostatic pressure of the immersion fluid prevents the water content of the item from causing steam explosion in the item while the microwave energy is applied. The method further includes heating the item immersed in the immersion fluid to a target temperature with the applied microwave energy, the target temperature being sufficient to achieve sterilization or pasteurization of the item.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a divisional application of U.S. patent applicationSer. No. 14/883,153, filed Oct. 14, 2015, which is a continuationapplication of PCT Application No. PCT/US15/29468, filed May 6, 2015,which claims priority to U.S. Provisional Application No. 61/990,066,filed on May 7, 2014, and 62/030,330, filed on Jul. 29, 2014.

BACKGROUND

Sterilization or pasteurization has been used in preserving foods,preventing sepsis in humans or animals, and in other fields. Forexample, food products can be sterilized or pasteurized to reduce oreliminate fungi, bacteria, viruses, spore forms, or other harmfulmicrobiological organisms that may cause spoilage or even food-bornediseases. One sterilization or pasteurization technique includes heatingfood products with hot air, hot water, or steam. Heating in such amanner, however, can result in poor taste, texture, color, or smell ofthe food products. Also, such heating technique can be energyinefficient and may require long processing time.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating a processing system usefulfor sterilization or pasteurization in accordance with embodiments ofthe disclosed technology.

FIG. 2 is a perspective diagram illustrating a carrier assembly suitablefor the processing system of FIG. 1 in accordance with embodiments ofthe disclosed technology.

FIG. 3 is a perspective diagram illustrating a partial heating sectionsuitable for the processing system of FIG. 1 in accordance withembodiments of the disclosed technology in accordance with embodimentsof the disclosed technology.

FIG. 4 is a perspective diagram illustrating an example divider suitablefor the processing system of FIG. 1 in accordance with embodiments ofthe disclosed technology.

FIGS. 5A-5C are schematic diagrams of preheating, tempered, and coolingfluid supplies suitable for the preheating section, heating section, andcooling section of the processing system of FIG. 1, respectively, inaccordance with embodiments of the disclosed technology.

FIG. 6 is a schematic diagram illustrating another processing systemuseful for sterilization or pasteurization in accordance withembodiments of the disclosed technology.

FIG. 7A is a perspective view of an example transport carrier suitablefor the processing system of FIG. 1 in accordance with embodiments ofthe disclosed technology.

FIG. 7B is a top view of an example transport carrier having lateralmembers in accordance with embodiments of the disclosed technology.

FIG. 7C is a side cross-sectional view of an example lateral membersuitable for the transport carrier of FIG. 7B in accordance withembodiments of the disclosed technology.

FIGS. 8A-8E are top views of carriers with various structuralconfigurations and corresponding example heating profiles in accordancewith embodiments of the disclosed technology.

FIG. 9 is a flowchart illustrating a process of adjusting operation of aprocessing system of FIG. 1 for sterilization or pasteurization inaccordance with embodiments of the disclosed technology.

FIG. 10 is a schematic cross-sectional diagram illustrating anotherprocessing system useful for sterilization or pasteurization inaccordance with embodiments of the disclosed technology.

FIGS. 11A and 11B are schematic top and end views of a transport carrierassembly suitable for the processing system of FIG. 10.

FIG. 12 is a schematic top view of another transport carrier assembly inaccordance with embodiments of the disclosed technology.

DETAILED DESCRIPTION

Various embodiments of processing systems, components, and compositionsfor sterilization or pasteurization and associated methods of operationare described herein. In the following description, specific details ofsystems, components, and operations are included to provide a thoroughunderstanding of certain embodiments of the disclosed technology. Aperson skilled in the relevant art will also understand that thetechnology may have additional embodiments. The technology may also bepracticed without several of the details of the embodiments describedbelow with reference to FIGS. 1-11B.

As used herein, the term “sterilization” generally refers to a processthat eliminates or removes all forms of fungi, bacteria, viruses, sporeforms, or other microbiological organisms present in food products,medication, biological culture media, or other suitable items. Also usedherein, the term “pasteurization” generally refers to a partialsterilization process in which microbiological organisms are partiallybut not completely eliminated or removed. The term “item” generallyrefers to any suitable article of manufacture that may be sterilized orpasteurized. Example items include, without limitation, food products,medical supplies, consumer products, and/or other suitable articles. Theterm “food product” generally refers to any food items suitable forhuman or animal consumption. Examples of a food product include, withoutlimitation, packaged foods, canned foods, dairy products, beer, syrups,water, wines, and juices.

As discussed above, sterilization or pasteurization by heating foodproducts with hot air, hot water, or steam may result in poor taste,texture, color, smell, or other adverse effects. During the heatingprocess, a surface or exterior portion of the food products may beexcessively heated in order to achieve a desired interior temperature.Such excessive heating is one factor that may cause the foregoingadverse effects in the food products. Several embodiments of thedisclosed technology utilize microwave to heat items (e.g., a foodproduct) immersed in an immersion fluid (e.g., tempered water) tosterilize or pasteurize the items. As discussed in more detail below,several embodiments of the disclosed technology requires less processingtime than conventional techniques, and can produce repeatable andgenerally uniform temperature profiles in the items to achievesterilization or pasteurization in an efficient and cost-effectivemanner.

FIG. 1 is a schematic diagram illustrating a processing system 100useful for sterilization or pasteurization of items 101 (e.g., a foodproduct) contained in transport carriers 108 in accordance withembodiments of the disclosed technology. As shown in FIG. 1, theprocessing system 100 can include a preheating section 102, a heatingsection 104, and a cooling section 106 (collectively referred to as“sections”) coupled to one another in series. In the illustratedembodiment, the processing system 100 also includes an optional holdingsection 105 between the heating section 104 and the cooling section 106.In other embodiments, the optional holding section 105 may have othersuitable configurations, one example of which is described in moredetail below with reference to FIG. 6. In further embodiments, theholding section 105 may be eliminated. Even though certain components orsections are illustrated in FIG. 1, the processing system 100 can alsoinclude additional and/or different components. For example, theprocessing system 100 can also include a process logic controller,pneumatic lifts, strainers, filters, sensors (e.g., level sensors, flowmeters, pressure gauges, etc.), and/or other suitablemechanical/electrical components.

As shown in FIG. 1, the sections may be configured to circulate and/orhold an immersion fluid 110. In certain embodiments, the immersion fluid110 can include water, and one or more of the sections may be coupled toa corresponding fluid supplies. For example, the preheating section 102can be coupled to a preheating fluid supply 132. The cooling section 106is coupled to a cooling fluid supply 136. In the illustrated embodiment,the heating section 104 and the optional holding section 105 are bothcoupled to a tempered fluid supply 134. In other embodiments, theheating section 104 and the optional holding section 105 may each becoupled to a corresponding tempered fluid supplies (not shown).

Each of the fluid supplies 132, 134, and 136 can be configured toprovide and circulate the immersion fluid 110 at an operatingtemperature. For example, in certain embodiments, the preheating fluidsupply 132 can provide and circulate the immersion fluid 110 at atemperature approximately equal to or above a preheating temperature(e.g., 60° C.) of the items 101 in the preheating section 102. Thetempered fluid supply 134 can provide and circulate the immersion fluid110 at a temperature approximately equal to or above a desired heatingtemperature (e.g., 90° C.) of the items 101 in the heating section 104.The preheating temperature is generally lower than the heatingtemperature in the heating section 104. Examples of the heating fluidsupply 132, tempered fluid supply 134, and the cooling fluid supply 136are described in more detail below with reference to FIGS. 5A-5C,respectively. In other embodiments, the immersion fluid 110 may alsoinclude fat, oil, polymeric solvents, and/or other suitable fluid inliquid or semi-liquid form.

Also shown in FIG. 1, one or more dividers 111 (shown individually asfirst divider 111 a and second divider 111 b) may be configured tocontrollably isolate the immersion fluid 110 between adjacent sectionswhile allowing the transport carriers 108 to pass through. For example,in the illustrated embodiment, the first divider 111 a can controllablyisolate the immersion fluid 110 between the preheating section 102 andthe heating section 104. The second divider 111 b can controllablyisolate the immersion fluid 110 between the heating section 104 (andoptional holding section 105) and the cooling section 106. In otherembodiments, the processing system 100 can also include additionaland/or different placement of dividers 111. For example, an additionaldivider (not shown) may be between the heating section 104 and theholding section 105.

The one or more dividers 111 can each include suitable mechanical and/orelectrical components configured to at least partially seal theimmersion fluid 110 from flowing to adjacent sections. For example, inone embodiment, a divider 111 can include a pretension door constructedfrom a flexible material (e.g., rubber), a rigid material (e.g.,plastic), or other suitable materials. The pretension door can benormally closed except when allowing the transport carriers 108 to passthrough. In another embodiment, a divider 111 can include an actuatedgate synchronized with the passing of the transport carriers 108 throughthe actuated gate. An example of the actuated gate is described belowwith reference to FIG. 4. In further embodiments, a divider 111 caninclude other suitable actuated or passive components and/orconfigurations.

The preheating section 102 is configured to receive one or more of thetransport carriers 108 carrying items 101 to be sterilized orpasteurized. The transport carriers 108 are shown in FIG. 1 as eachcarrying three items 101 for illustration purposes. In otherembodiments, the transport carriers 108 can carry two, four, five, six,or any other suitable number of items 101. In one embodiment, thetransport carriers 108 may be received in batches. For example, thetransport carriers 108 with the items 101 may be loaded into thepreheating section 102 before sterilization or pasteurization processingis started and reloaded once the processing of a previous batch isfinished. In other embodiments, the transport carriers 108 may bereceived in a continuous manner from, for example, a conveyer belt (notshown), a manual loading dock (not shown), and/or other suitable sources(not shown). In further embodiments, the transport carriers 108 may bereceived in semi-continuous or other suitable manners.

The preheating section 102 is also configured to homogenize temperaturesof the received items 101 in the transport carriers 108 to a preheatingtemperature. In one embodiment, the preheating temperature can be about60° C. In other embodiments, the preheating temperature can be 40° C.,50° C., or any other suitable temperatures. In the illustratedembodiment, the immersion fluid 110 supplied by the preheating fluidsupply 132 is used to preheat and/or homogenize the temperatures of theitems 101 to the preheating temperature. In other embodiments, steam,hot oil, and/or other thermal media may also be used.

In the illustrated embodiment, the preheating section 102 includes acarrier assembly 112 having an inlet 112 a and an outlet 112 b that isproximate to the first divider 111 a. The carrier assembly 112 caninclude a vessel, tank, cartridge, or other suitable structures. Incertain embodiments, the carrier assembly 112 can have a volumesufficient to provide a residence time such that temperatures of theitems 101 in the transport carriers 108 can be at least generallyhomogenized when passing from the inlet 112 a to the outlet 112 b of thecarrier assembly 112. In other embodiments, the carrier assembly 112 canalso have other suitable volumes, structures, shapes, or components.

The carrier assembly 112 can also have a height H relative to theheating section 104 to exert a hydrostatic pressure on the items in theheating section 104. As discussed in more detail below, the hydrostaticpressure exerted on the individual items 101 may prevent or at leastreduce the risk of steam explosion during heating in the heating section104. In one embodiment, the height H can be about 5 meters. In otherembodiments, the height H can be 4 meters, 6 meters, or any othersuitable distances. In any of the foregoing embodiments, the height Hmay be adjusted based on at least one of (1) a desired heatingtemperature of the items 101, (2) a water content of the items 101, (3)a temperature of the immersion fluid 110 in the heating section 104, (4)power of microwave energy delivered to the items 101 in the heatingsection, or other suitable factors.

The carrier assembly 112 can also include a transport mechanismconfigured to transfer the individual transport carriers 108 to theheating section 104. As shown in FIG. 1, one example transport mechanismcan include one or more rollers 122 proximate the outlet 112 b of thecarrier assembly 112. The one or more rollers 122 can be configured tocarry one of the transport carriers 108 to the heating section 104through the outlet 112 b and via the first divider 111 a. One examplecarrier assembly 112 having rollers 122 is described in more detailbelow with reference to FIG. 2.

In other embodiments, the rollers 122 may be omitted from the carrierassembly 112. Instead, the carrier assembly 112 may include mechanicalmovers, fluid jets, compressed gas, and/or other suitable transportmechanisms to transfer the individual transport carriers 108 from thepreheating section 102 to the heating section 104. In furtherembodiments, the preheating section 102 can also include additionaland/or different components. For example, the preheating section 102 mayinclude two, three, or other suitable numbers of carrier assemblies (notshown) arranged in series, parallel, or in other suitable manners.

The heating section 102 is configured to apply microwave energy to theitems 101 carried in the transport carriers 108 while the items 101 areimmersed in the immersion fluid 110 and subject to a hydrostaticpressure of the immersion fluid 110. The applied microwave energy may besufficient to raise a temperature (e.g., an interior temperature) of theitems 101 to or above a target heating temperature sufficient to achievesterilization or pasteurization. The interior temperature can be acenter temperature or a temperature proximate to a central region of theindividual items 101. In one embodiment, the target heating temperaturecan be about 90° C. In other embodiments, the target heating temperaturecan be 70° C., 80° C., 100° C. or other suitable temperature values.

The heating section 104 can include a transport unit 113 coupled to oneor more microwave assemblies 114. The transport unit 113 can beconfigured to receive the transport carriers 108 carrying the items 101from the preheating section 102. The transport unit 113 can also beconfigured to convey the received transport carriers 108 with the items101 through the heating section 104 to be irradiated by microwave energyfrom the microwave assemblies 114 (indicated by arrows 117). As shown inFIG. 1, the transport unit 113 includes a transport housing 123, aplurality of rollers 122, and one or more microwave windows 125 in thetransport housing 123. The microwave windows 125 can each include anopening with a microwave transmissive component (e.g., a glass orplastic plate). One example transport unit 113 is described in moredetail below with reference to FIG. 3.

The microwave assemblies 114 are each configured to apply microwaveenergy to both sides of the items 101 simultaneously as the individualitems 101 carried by the transport carriers 108 are moved through thetransport unit 113. As shown in FIG. 1, each microwave assembly 114includes two sets of a microwave source 116 coupled to a microwave guide118 on opposite sides of the transport unit 113. The microwave source116 can include a single-mode microwave source at a particular frequency(e.g., 950 MHz) or other suitable microwave sources. The microwave guide118 can include a conical, trapezoidal, or other suitable shapedstructure configured to direct the microwave energy 117 from themicrowave sources 116 to the items 101 via the corresponding microwavewindows 125 in the transport unit 113. In FIG. 1, two side-by-sidemicrowave assemblies 114 are shown for illustration purposes. In otherembodiments, the heating section 104 can include one, three, or anyother suitable number of microwave assemblies 114. In furtherembodiments, the microwave assemblies 114 can be spaced apart from eachother. In yet further embodiments, the microwave assemblies 114 may bein other suitable arrangements.

The optional holding section 105 can be configured to at leastapproximately maintain the interior temperature of the heated items 101for a period of time (referred to as a holding time) to facilitate oreffectuate sterilization or pasteurization. Without being bound bytheory, it is believed that at least partial removal of certainmicrobiological organisms (e.g., bacteria) requires maintaining thetemperature of the items 101 for a period of time. For example, milk maybe pasteurized by heating milk to 72° C. for 15 seconds or 63° C. for 30minutes. In one embodiment, the holding section 105 can include aholding tank 124 with a volume sufficient to provide a residence timethat is equal to or above the holding time. The holding tank 124 canalso include one or more rollers 122 configured to convey the transportcarriers 108 to the cooling section 106. In other embodiments, theholding section 105 can include a holding tank with other suitablestructures, volumes, and/or configurations. In the illustratedembodiment, the optional holding section 105 is shown as being at alower elevation than the heating section 104. In other embodiments, theholding section 105 may be at the same elevation as or higher elevationthen the heating section 104. In further embodiments, the holdingsection 105 may have other suitable arrangements relative to the heatingsection 104.

The cooling section 106 can be configured to reduce an overalltemperature or interior temperature of the heated items 101 to roomtemperature (e.g., 15° C.) or other suitable temperatures for handling,transporting, and/or storage. As shown in FIG. 1, the cooling section106 can include a transport vessel 126 with rollers 122 generallysimilar to the transport vessel 112 of the preheating section 102. Incertain embodiments, the transport vessel 126 can have a volume toprovide a sufficient residence time to reduce the overall or interiortemperature of the items 101 from the heating section 104 and theoptional holding section 105. In other embodiments, the transport vessel126 may be configured to operate in a batch mode, and thus may have anysuitable volumes.

In operation, the preheating section 102 receives the items 101 in thetransport 108 and heat and/or homogenize temperatures of the items 101with the immersion fluid 110 to the preheating temperature. Thepreheating section 102 may be operated in various modes. For example, inone embodiment, the preheating section 102 may be operated in batches. Aplurality of transport carriers 108 with corresponding items 101 areinitially received at the transport assembly 112. The preheating fluidsupply 132 then provides water at a heating temperature (e.g., 80° C.)to heat and/or homogenize temperatures of the items 101 to thepreheating temperature. Once the temperatures of the items 101 aregenerally homogenized, the transport mechanism (e.g., the rollers 122)can be activated to convey each transport carriers 108 to the heatingsection 104 via the first divider 111 a.

In another embodiment, the preheating section 102 may be operated in agenerally continuous mode. For example, the preheating fluid supply 132can first establish circulation of the immersion fluid 110 at atemperature (e.g., 80° C.) in the transport assembly 112. Subsequently,the transport assembly 112 can receive the transport carriers 108 viathe inlet 112 a. As the transport carriers 108 travels from the inlet112 a toward the outlet 112 b, the circulated water can heat and/orhomogenize the temperatures of the items 101. Then, the transportmechanism (e.g., the rollers 122) can continuously convey the individualtransport carriers 108 to the heating section 104 via the first divider111 a. In further embodiments, the preheating section 102 may beoperated in other suitable manners.

The heating section 104 can then receive the items 101 with generallyhomogenized temperatures from the preheating section 102 and applyadditional heat via microwave energy to the items 101. The temperedfluid supply 134 can initially establish a circulation of the immersionfluid 110 in the heating section 104 (and optional holding section 105).The transport unit 113 of the heating section 104 can then receive thetransport carriers 108 with the items 101 via the first divider 111 a.The rollers 122 in the transport unit 113 then conveys the individualtransport carriers 108 to the optional holding section 105 along adirection (illustrated by arrow 127). As the items 101 in the immersionfluid 110 move past the microwave windows 125, the microwave sources 116apply microwave energy to both sides of the items 101 to raise aninterior temperature of the items 101 to the target heating temperature.Subsequently, the rollers 122 in the transport unit 113 can convey theheated items 101 in the transport carriers 108 to the optional holdingsection 105.

The optional holding section 105 can receive the items 101 heated to thetarget heating temperature from the heating section 104 and generallymaintain the items 101 at that temperature for a period of time (e.g.,10 minutes). As discussed above, by maintaining the items 101 at or nearthe target heating temperature can reduce or remove microbiologicalorganisms in the items 101. At the end of the period of time, theoptional holding section 105 conveys the transport carriers 108 with theitems 101 to the cooling section 106. The cooling section 106 thenapplies the immersion fluid 110 from the cooling fluid supply 136 at acooling temperature (e.g., 15° C.) to reduce an overall or interiortemperature of the items 101 to room temperature or other suitabletemperatures. The cooled items 101 can then be unloaded from the coolingsection 106 to be further processed and/or stored.

Several embodiments of the processing system 100 can be used toefficiently sterilize or pasteurize items 101 without or with reducednegative effects on the items 101 than conventional techniques. Unlikeconventional techniques in which items 101 are heated by heating foodproducts with hot air, hot water, or steam, items 101 are heated bymicrowave. As a result, interior temperatures of the items 101 can bemore efficiently raised than conventional heating techniques.

Several embodiments of the processing system 100 can also be used toefficiently sterilize or pasteurize items 101 without requiringpressurization of the sections in the processing system 100. Instead, atleast some sections of the processing system 100 may be open toatmosphere. As discussed above, the items 101, such as packaged foodproducts, typically include a certain amount of water content. Thus, theapplied microwave energy in the heating section 104 may generate steamthat cause explosion or rupture of the packaged food products. In someother processing systems, the sections are pressurized, for example,with an inert gas or air to prevent such steam explosion. However, suchpressurization requires the sections be designed as pressure vessels,and thus increasing the costs of manufacturing and installation as wellas operating complexity. In contrast, several embodiments of theprocessing system 100 utilizes the a hydrostatic pressure of theimmersing fluid 110 on the items 101 to prevent or at least reduce therisk of steam explosion during heating, and thus avoid the need topressurize the sections. The immersion fluid 110 can also help tohomogenize temperatures of the items during preheating, heating, and/orcooling.

FIG. 2 is a perspective diagram illustrating an example carrier assembly130 suitable for the preheating section 102 or the cooling section 106of the processing system 100 of FIG. 1 in accordance with embodiments ofthe disclosed technology. As shown in FIG. 2, the carrier assembly 130can include a housing 131 having an inlet 131 a with an inlet flange 144a and an outlet 131 b with an outlet flange 144 b. A back panel of thehousing 131 is removed to show the transport carriers 108 forillustration purposes. In the illustrated embodiment, the housing 131has a generally rectangular cross section between a first end 137 a anda second end 137 b. The inlet flange 144 a and the outlet flange 144 bare generally perpendicular to each other. In other embodiments, thecarrier assembly 130 can have a trapezoidal, cylindrical, and/or othersuitable cross sections sized and shaped to receive a plurality oftransport carriers 108. In further embodiments, the carrier assembly 130can also include friction fittings and/or other suitable couplers inaddition to or in lieu of the inlet and/or outlet flanges 144 a and 144b.

In the illustrated embodiment in FIG. 2, the carrier assembly 130 caninclude a plurality of rollers 122 proximate the second end 137 b of thehousing 131. The rollers 122 are configured to carry the bottom-mosttransport carrier 108 to exit the housing 131 via the outlet 131 b, asindicated by an arrow 139. In one embodiment, the rollers 122 can befriction rollers. In other embodiments, the rollers 122 can includeother suitable types of rollers. In further embodiments, the carrierassembly 130 can also include additional and/or different conveyingcomponents. For example, in certain embodiments, the carrier assembly130 can also include a pneumatic push rods (not shown) proximate to thesecond end 137 b of the housing 131 to carry the bottom-most transportcarrier 108 to exit the housing 131 via the outlet 131 b.

Though not shown in FIG. 2, the carrier assembly 130 can include a fluidinlet (e.g., a fluid distributer) and a fluid outlet (e.g., a nozzle) onthe housing 131 to allow the immersion fluid 110 (FIG. 1) from thepreheating fluid supply 132 (FIG. 1) or the cooling fluid supply 136(FIG. 1) to circulate in an interior region 133 of the housing 131. Thehousing 131 can also include baffles, diverters, and/or other suitableflow modifying components configured to allow generally even flow of theimmersion fluid 110 in the housing 131.

In operation, the carrier assembly 130 can receive a plurality oftransport carriers 108 in a stack or other forms via the inlet 131 a.The rollers 122 carries the bottom-most transport carrier 108 along thedirection 139 to exit the outlet 131 b. As the bottom-most transportcarrier 108 exits the outlet 131 b, another transport carrier 108 movesdownward toward the second end 137 b of the housing 131 to be carriedthrough the outlet 131 b. The process continues until no more transportcarriers 108 are left in the housing 131.

FIG. 3 is a perspective diagram illustrating an example heating section104 suitable for the processing system 100 of FIG. 1 in accordance withembodiments of the disclosed technology in accordance with embodimentsof the disclosed technology. As shown in FIG. 3, the heating section 104can include a microwave assembly 114 coupled to a transport unit 113.Even though only one microwave assembly is shown for clarity in FIG. 3,the heating section 104 can include an additional microwave assemblies114 (FIG. 1) coupled to the transport unit 113. In other embodiments,the heating section 104 may include multiple additional microwaveassemblies (not shown) in any suitable arrangements.

As shown in FIG. 3, the microwave assembly 114 can include a microwavesource 116 coupled to a first end 118 a of a microwave guide 118 via aset of flanges 152. As discussed above with reference to FIG. 1, themicrowave source 116 can include a single-mode or other suitable typesof a microwave generator. In the illustrated embodiment, a second end118 b of the microwave guide 118 is coupled to the microwave window 125a of the transport unit 113. The microwave guide 118 also includes foursidewalls 153 extending between the first end 118 a and the second end118 b. Each of the sidewalls 153 has a generally trapezoidal shape. Inother embodiments, the microwave guide 118 can also include othersuitable structures with suitable shapes and sizes.

In the illustrated embodiment, the microwave assembly 118 also includesone or more microwave tuners 154 carried by one or more sidewalls 153 ofthe microwave guide 118. The microwave tuners 154 can be configured toadjust a load of microwave energy delivered from the microwave source116 to the items 101 (FIG. 1) via the microwave window 125 a. Themicrowave tuners 154 can include one or more mechanical slide-screwtuners, manual impedance tuners, automated impedance tuners, or othersuitable types of microwave tuners. In other embodiments, the microwavetuners 154 may have other suitable placements on the microwave assembly114 and/or the transport unit 113. In further embodiments, the microwavetuners 154 may be eliminated.

As shown in FIG. 3, the transport unit 113 includes a transport housing123 with a plurality of rollers 122. In the illustrated embodiment, thetransport housing 123 has a generally rectilinear shape with flanges 155at a first end 151 a and a second end 151 b. The transport housing 123has a microwave window 125 a at a first side 150 a and another microwavewindow 125 b at the opposite second side 150 b. In one embodiment, thefirst and second windows 125 a and 125 b may be generally aligned witheach other. In other embodiments, the first and second windows 125 a and125 b may be offset from each other or have other suitable arrangements.The rollers 122 are positioned side by side and proximate the secondside 150 b and thus forming a channel 156 through which the transportcarriers 108 (FIG. 1) may be carried by the rollers 122 from the firstend 151 a to the second end 151 b. In other embodiments, the transportunit 123 can also have other suitable structures, shapes, and sizessuitable to deliver microwave energy to the items 101 (FIG. 1) carriedon the transport carriers 108.

As shown in FIG. 3, the carrier assembly 130 can include a fluid inlet157 a (e.g., a fluid distributer) and a fluid outlet 157 b (e.g., anozzle) on the transport housing 123 to allow the immersion fluid 110(FIG. 1) from the tempered fluid supply 134 (FIG. 1) to circulate in thechannel 156 of the transport housing 123. The transport housing 123 canalso include baffles, diverters, and/or other suitable flow modifyingcomponents configured to allow generally even flow of the immersionfluid 110 in the transport housing 123.

In operation, individual transport carriers 108 carrying items 101 arereceived at the first end 151 a of the transport housing 123 while theimmersion fluid 110 from the tempered fluid supply 134 fills andcirculates in the channel 156. The rollers 122 can then carry theindividual transport carriers 108 from the first end 151 a to the secondend 151 b. The items 101 can then receive microwave energy from themicrowave source 116 while immersed in the immersion fluid 110 when theitems 101 pass under/above the microwave windows 125 a and 125 b.

In one embodiment, when a transport carrier 108 is generally alignedwith the microwave windows 125 a and 125 b, the rollers 122 may bestopped. The microwave source 116 may then be turned on to delivermicrowave energy to the items 101 on the transport carrier 108 for aperiod of time (e.g., about 10 seconds to about 3 minutes).Subsequently, the rollers 122 are turned on to carry the transportcarrier 108 toward the second end 151 b. In another embodiment, therollers 122 may be slowed but not stopped when the transport carrier 108is at least partially exposed through the microwave windows 125 a and126 b while the microwave source 116 is turned on to deliver microwaveenergy through the microwave windows 125 a and 125 b. In a furtherembodiment, the rollers 122 may carry the transport carriers 108 throughthe channel 156 at a constant speed. In yet further embodiments, therollers 122 may carry the transport carriers 108 through the channel 156in other suitable manners.

FIG. 4 is a perspective diagram illustrating an example divider 111suitable for the processing system 100 of FIG. 1 in accordance withembodiments of the disclosed technology. As shown in FIG. 4, the divider111 can include a pair of flanges 160 a and 160 b spaced apart from eachother by a divider channel 161 and a gate 162 positioned in the dividerchannel 161. In the illustrated embodiment, the gate 162 includes ablocking member 163 attached to one or more lifting members 164 (two areshown for illustration purposes). The blocking member 163 can include aplate, slab, sheet, or other suitable structures constructed from ametal, alloy, plastic, rubber, or any other suitable materials withsufficient rigidity. In one embodiment, the lifting members 164 may beformed integral with the blocking member 163. In other embodiments, thelifting members 164 may be attached to the blocking member 163 with oneor more fasteners, glue, or other suitable attachment mechanisms (notshown). Though not shown in FIG. 4, the divider 111 can also includeseals, rails travel guides, and/or other suitable components attached onand/or formed in the flanges 160 a and 160 b and/or the gate 162.

In one mode of operation, the lifting members 164 may be actuated by anelectrical motor, a pneumatic cylinder, and/or other suitable drivingmechanisms (not shown) to push the blocking member 163 into the dividerchannel 161 between the flanges 160 a and 160 b, as indicated by arrow166 a. The blocking member 163 can thus at least partially isolate theimmersion fluid 110 (FIG. 1) on either side of the flange 160 a or 160b. In another mode of operation, the lifting members 164 may also beactuated to remove the blocking member 163 from the divider channel 161,as indicated by arrow 166 b. As shown in FIG. 4, once the blockingmember 163 is at least partially removed, a passage 168 forms throughthe flanges 160 a and 160 b allowing transport carriers 108 (FIG. 1) topass through.

FIGS. 5A-5C are schematic diagrams of preheating, tempered, and coolingfluid supplies 132, 134, and 136 suitable for the preheating section102, heating section 106, and cooling section 108 of the processingsystem 100 of FIG. 1, respectively, in accordance with embodiments ofthe disclosed technology. In FIGS. 5A-5C, identical reference numbersidentify elements similar in structure and/or function. Even thoughparticular components are shown in FIGS. 5A-5C, the fluid supplies 132,134, and 136 may also include a flow meter, pressure gauge, pressuretransmitter, valve position switches/transmitters, and/or other suitablecomponents (not shown).

As shown in FIG. 5A, the preheating fluid supply 132 can include acirculating pump 170, a steam heat exchanger 172, a steam valve 174, atemperature sensor 178, and a controller 176 operatively coupled to oneanother. The circulating pump 170 can include a centrifugal pump, a gearpump, or other suitable types of pump. The steam heat exchanger 172 caninclude a plate-and-tube, plate, or other suitable types of heatexchanging component. The temperature sensor 178 can include athermocouple, a resistance temperature detector, or other suitable typesof temperature sensor. The steam valve 174 can include an actuated globevalve, butterfly valve, ball valve, or other suitable types of valve.The controller 176 can include a single-loop controller or a controlmodule of a programmable process controller.

In operation, the circulating pump 170 receives the immersion fluid 110from the preheating section 102 (FIG. 1) and moves the receivedimmersion fluid 110 to the steam heat exchanger 172. Steam (e.g., 60Psig steam) is introduced through the steam valve 174 to heat theimmersion fluid 172 while the immersion fluid 172 passes through thesteam heat exchanger 172. The temperature sensor 178 measures thetemperature of the immersion fluid 110 exiting the steam heat exchanger172 and provides the measurement to the controller 176. The controller176 can then adjust the steam valve 174 based on a setpoint for thetemperature of the immersion fluid 110 exiting the steam heat exchanger172 and the measurements from the temperature sensor 178.

In the illustrated embodiment, the introduced steam is collected ascondensate after passing through the heat exchanger 172. The collectedcondensate may then be recycled, drained, or otherwise processed. Inother embodiments, the heat exchanger 172 may be substituted by asteam-water mixer (not shown) that is configured to directly mix theintroduced steam with the immersion fluid 110.

As shown in FIG. 5B, the tempered fluid supply 134 can be generallysimilar to the preheating fluid supply 132 shown in FIG. 5A excepthaving a cooling heat exchanger 173 in series with the steam heatexchanger 172 and a cooling water valve 175 configured to introducecooling water to the cooling heat exchanger 173. Even though the coolingheat exchanger 173 is shown in FIG. 5B as downstream from the heatexchanger 172, in other embodiments, the cooling heat exchanger 173 canalso be positioned upstream of the steam heat exchanger 172 or in othersuitable places.

In operation, the controller 176 can adjust both the cooling water valve175 and the steam valve 174 to achieve a setpoint for the temperature ofthe immersion fluid 110 to the heating section 104 (FIG. 1). Forexample, the controller 176 may be configured to perform split controlaccording to which positive control actions are directed to the steamvalve 174 while negative control actions are directed to the coolingwater valve 173. Thus, the immersion fluid 110 may be heated by steamwhen passing through the steam heat exchanger 172 and cooled by coolingwater when passing through the cooling heat exchange 173. In otherexamples, the controller 176 may also be configured to perform stepcontrol, threshold control, or other suitable control schemes.

As shown in FIG. 5C, the cooling fluid supply 136 can be generallysimilar to the tempered fluid supply 134 of FIG. 5B except the coolingfluid supply 136 does not include the steam heat exchanger 172 or thesteam valve 174. In operation, the cooling water valve 175 admitscooling water to the cooling heat exchanger 173 to remove heat from theimmersion fluid 110. The temperature sensor 178 measures the temperatureof the immersion fluid 110 exiting the cooling heat exchanger 173 andprovides the measurements to the controller 176. The controller 176 canthen adjust the cooling water valve 175 based on a setpoint for thetemperature of the immersion fluid 110 exiting the cooling heatexchanger 173 and the measurements from the temperature sensor 178.

FIG. 6 is a schematic diagram illustrating another processing system100′ useful for sterilization or pasteurization in accordance withembodiments of the disclosed technology. As shown in FIG. 6, theprocessing system 100′ can be generally similar to that of FIG. 1 exceptthat the preheating section 102 and the cooling section 106 can be at agenerally similar elevation H with respect to the heating section 104.Also, the processing system 100′ in FIG. 6 does not include the optionalholding section 105. Instead, the processing system 100′ includes atransport section 107 between the heating section 104 and the coolingsection 106. The transport section 107 can be at an elevation generallysimilar to that of the heating section 104. In other embodiments, thetransport section 107 may be omitted, and the heating section 104 may becoupled directly to the cooling section 106. In further embodiments, theprocessing system 100′ may include other suitable components,assemblies, and sections in suitable arrangements.

FIG. 7A is a perspective view of an example transport carrier 108suitable for the processing system 100 of FIG. 1 in accordance withembodiments of the disclosed technology. As shown in FIG. 7A, thetransport carrier 108 can include a carrier base 180 carrying one ormore cross members 182. The carrier base 180 can have any suitable shapebased on at least one of a shape or size of the items 101 (FIG. 1) to becarried thereon. For example, in the illustrated embodiment, the carrierbase 180 has a generally rectilinear shape with a first side 181 a and asecond side 181 b (collectively referred to as side or sides 181)extending between a first end 180 a and a second end 180 b of the base180. In other embodiments, the carrier base 180 can have a generallyoval, square, and/or other suitable shapes.

As shown in FIG. 7A, the first and second sides 181 a and 181 b eachinclude a perforated plate 185 having a first support 184 and a secondsupport 186 extending away from the perforated plate 185. The firstsupport 184 extends toward an interior region of the carrier base 180,and the second support 186 extends in a direction opposite of the firstsupport 184. Both the first and second supports 184 and 186 extendtransversely between the first end 180 a and the second end 180 b. Thefirst support 184 may be configured to support one or more items 101carried in the transport carrier 108. The second support 186 may beconfigured to engage the rollers 122 (FIG. 1) or other suitablecomponents of the processing system 100. The first and second ends 180 aand 180 b include one or more end bars 183 (three are shown at each endfor illustration purposes). In other embodiments, the first and secondends 180 a and 180 b can include the cross members 182 instead.

The cross member 182 can include an elongated component extendingbetween the first and second sides 181 a and 181 b. The cross member 182can have a generally circular, rectangular, cubic, oval, or any othersuitable cross-sectional are. In the illustrated embodiment, one pair ofcross members 182 are shown for illustration purposes. In otherembodiments, the carrier base 180 can carry two, three, four, or anysuitable number of cross members 182 generally parallel to one another.In further embodiments, the carrier base 180 may carry one cross member182 at a particular position between the first and second ends 180 a and180 b instead of two cross members 182, as illustrated in FIG. 7A.

In any of the foregoing embodiments, various components of the carrierbase 180 and the cross members 182 may be constructed from stainlesssteel, aluminum, plastics, or other suitable materials with sufficientmechanical strength. In one example, the first and second sides 181 aand 181 b and the first and second ends 180 a and 180 b may beconstructed from stainless steel while the first supports 184 and thecross members 182 constructed from polyetherimide, polyether etherketone, or other suitable plastic materials. In another example, thecarrier base 180 and the cross members 182 can all be constructed fromstainless steel or a plastic material. In further examples, the carrierbase 180 and the cross members 182 may have other suitable combinationsof construction materials.

In operation, the carrier base 180 can carry and support one, two, orany suitable number of items 101. For example, the items 101 may befastened or otherwise attached to the cross members 182 and/or the firstand second ends 180 a and 180 b using meshes, as discussed in moredetail below with reference to FIG. 7B. In other embodiments, the items101 may also be fastened or otherwise attached using clips, ropes,belts, hangers, and/or other suitable attachment mechanisms.

Even though the transport carrier 108 is illustrated in FIG. 7A ashaving particular components, in other embodiments, the transportcarrier 108 can also include additional and/or different components inother suitable arrangements. For example, the carrier base 180 may alsoinclude a base member (e.g., a plate, a sheet, a mesh, etc. not shown)fastened to and/or supported on the first supports 184. In furtherembodiments, the transport carrier 108 may also include lateral members188 (FIG. 7B), as discussed in more detail below with reference to FIGS.7B and 7C.

FIG. 7B is a top view of a transport carrier 108 having lateral membersin accordance with embodiments of the disclosed technology. As shown inFIG. 7B, the transport carrier 108 can include a first lateral member188 a proximate to the first side 181 a and a second lateral member 188b proximate to the second side 181 b. The first and second lateralmembers 188 a and 188 b extend transversely between the first end 180 aand the second end 180 b. In one embodiment, the lateral members 188 aand 188 b can be generally similar in shape and size as the first andsecond sides 181 a and 181 b, respectively. In other embodiments, thelateral members 188 a and 188 b can have other suitable shapes andsizes. In further embodiments, the lateral members 188 a and 188 b mayhave different shape and/or size from each other. One example lateralmember 188 is discussed below with reference to FIG. 7C.

The first and second lateral members 188 a and 188 b may be movable andrelocated relative to the first and second sides 181 a and 181 b,respectively. In the illustrated embodiment in FIG. 7B, the firstlateral members 188 a and 188 b are shown as being spaced apart from thefirst and second sides 181 a and 181 b, respectively, by the samedistance D. In other embodiments, the first and second lateral members188 a and 188 b can be abutting the first and second sides 181 a and 181b, respectively, abutting the items 101, or be at other suitablelocations. In further embodiments, the first and second lateral members188 a and 188 b may be spaced apart from the first and second sides 181a and 181 b, respectively, at different distances (not shown).

As discussed in more detail below with reference to FIGS. 8A-8E, theinventors have recognized that certain structural features of thetransport carrier 108 can influence a heating profile of the individualitems 101. Such structural features can include material of constructionof the cross members 182, position of the lateral members 188 a and 188b, as well as material of construction of the lateral members 188 a and188 b. As a result, a target heating profile may be achieved by (1)selecting a material of construction for the individual cross members182 and/or lateral members 188 a and 188 b; and/or (2) adjusting aposition of the individual lateral members 188 a and 188 b relative tothe first and second sides 181 a and 181 b.

Also shown in FIG. 7B, the transport carrier 108 includes a mesh 189hanging from, clipped on, or otherwise attached to the cross members 182and/or the first and second ends 180 a and 180 b. The mesh 189 carries aplurality of the items 101. In the illustrated embodiment, the mesh 189is shown as having double layers having the items 101 between thelayers. In other embodiments, the mesh 189 can carry the items with onelayer and/or in other suitable manners. One mesh product (#G-632896801)suitable for the mesh 189 is provided by Greenbelt Industries, Inc. ofBuffalo, N.Y. As discussed above, in other embodiments, the transportcarrier 108 may include other suitable components configured to carrythe items 101.

FIG. 7C is a side cross-sectional view of an example lateral member 188suitable for the transport carrier 108 of FIG. 7B in accordance withembodiments of the disclosed technology. As shown in FIG. 7C, thelateral member 188 can include a base 192 having a plurality ofapertures 194. In the illustrated embodiment, the base 192 includes agenerally rectangular plate. In other embodiments, the base 192 can alsoinclude a sheet, a bar, a cylinder, or other suitable structures in anysuitable shapes. The apertures 194 can be shaped and sized to allow thecross members 182 (FIG. 7B) to pass through. Five apertures 194 areshown in FIG. 7C for illustration purposes. In other embodiments, thebase 192 can include two, three, four, six, seven, or any other suitablenumbers of apertures 194.

As shown in FIG. 7C, the base 192 can also include one or more openings195 extending from an edge 193 of the base 192 to a correspondingaperture 194. In the illustrated embodiment, two openings 195 are shownfor illustration purposes. In other embodiments, the base 192 caninclude one, three, or any other suitable number of openings 195. Incertain embodiments, the openings 195 can be threaded to engage apositioning element 196 (e.g., a set screw, a pin, a compressionfitting, etc.). In other embodiments, the openings 195 may beeliminated, and the base 192 may engage the cross members 182 viafriction, spring (not shown), magnets, or other suitable engagementmechanisms.

As discussed above, the inventors have recognized that certainstructural features of the transport carrier 108 can influence a heatingprofile of the individual items 101 upon application of microwaveenergy. Several tests were conducted to pasteurize items 101 having asimulated composition in a processing system generally similar to theprocessing system 100 of FIG. 1. The items 101 were carried in transportcarriers 108 generally similar to that shown in FIGS. 7A-7C and immersedin water.

The simulated composition is configured to show observable effects inresponse to heating under various temperature conditions. In certainembodiments, the simulated composition can include a combination of thefollowing components:

-   -   browning precursor(s);    -   a carrier;    -   a dielectric property modifier;    -   a viscosity modifier; and    -   water.        The browning precursors can include an amino acid (e.g., lysine,        leucine, asparagine, glycine, etc.) and a reducing sugar (e.g.,        ribose, glucose, glyceraldehyde, galactose, etc.). The carrier        can include a matrix material suitable to carry other components        of the simulated composition. Example carriers can include        potato, egg whites, and/or other suitable materials. The        dielectric property modifier can include sucrose, salt, or other        materials suitable for changing or influencing a dielectric        characteristic of the simulated composition. The viscosity        modifier can include Gellan gum, starches, vegetable gums,        pectin, or other suitable thickener, emulsifier, or stabilizer        of food compositions.

One example simulated composition used during testing include thefollowing in weight percentages:

-   -   Gellan gum: 0.5-1.5% with about 0-10 mM calcium chloride;    -   Sucrose: 0-50%;    -   Sodium chloride: 0-300 mM;    -   D-ribose: 0.5-2%;    -   Lysine: 0.5-2%; and    -   Water: 42.6-98.5%.        The foregoing composition may be prepared by the following        process:    -   Add Gellan gum to water and stir for about one hour at room        temperature;    -   Heat the Gellan gum and water to about 90° C.;    -   Add a determined amount of calcium chloride based on a desired        gel strength;    -   Stir at 90° C. for one minute and turn off heat;    -   Add ribose and lysine when mixture temperature is about 60° C.;        and    -   Pour mixture to a tray.

Without being bound by theory, it is believed that when an amino acid(e.g., lysine) is heated with a reducing sugar (e.g., D-ribose),D-ribose reacts with lysine through enolization under weak acidic orneutral conditions to cause browning of the simulated composition. Thedegree of browning or color change is related to the temperature atwhich the reaction occurs. As a result, by observing the color change ofthe simulated composition, a heating profile may be derived. Exampletechniques for observing the color change can include color temperaturemeasuring, light reflection measuring, and/or other suitable techniques.

Various components of the simulated composition can be adjusted to atleast approximately match a target material (e.g., a food product) inphysical characteristic. For example, an amount of calcium chloride maybe adjusted to achieve a gel strength or firmness of the simulatedcomposition based on a firmness of the target material. An amount ofdielectric property modifier may be adjusted to at least approximatelymatch the dielectric constant of the target material. An amount of theviscosity modifier may be adjusted to at least approximately match theviscosity of the target material. An amount of water may also beadjusted based on a water content or consistency of the target material.

Various embodiments of the simulated composition may be used forestablishing and/or adjusting operating characteristics of theprocessing system 100 of FIG. 1 (or similar processing systems). Forexample, the simulated composition may be used to calibrate thetransport carriers 108 when used in the processing system 100. Inanother example, the simulated composition may also be used to verifyheating efficacy of the processing system 100, for example, by observingcolor changes after processing. In a further example, the simulatedcomposition may also be used to determine a heating profile of theprocessing system 100 based on which the process may be adjusted toachieve a desired heating result.

FIGS. 8A-8E show results of the tests in accordance with embodiments ofthe disclosed technology. In particular, FIGS. 8A-8E show top views oftransport carriers 108 with various structural features andcorresponding example heating profiles determined by observing thesimulated composition. In particular, FIG. 8A shows a transport carrier108 having a plurality of stainless steel cross members 182 and twostainless steel lateral members 188. FIG. 8B shows a transport carrier108 having a plurality of polyetherimide cross members 182′ and twostainless steel lateral members 188. FIG. 8C shows a transport carrier108 having a plurality of polyetherimide cross members 182′ and twopolyetherimide lateral members 188′ spaced apart from both the first andsecond sides 181 a and 181 b as well as the items 101. FIG. 8D shows atransport carrier 108 having a plurality of polyetherimide cross members182′ and two polyetherimide lateral members 188′ spaced apart from thefirst and second sides 181 a and 181 b and abutting the items 101. FIG.8E shows a transport carrier 108 having a plurality of polyetherimidecross members 182′ and two polyetherimide lateral members 188′ spacedapart from the items 101 but abutting the first and second sides 181 aand 181 b.

As clearly shown in FIGS. 8A-8E, the various structural features of thetransport carriers 108 caused the temperature profiles of the items 101to differ significantly. Without being bound by theory, it is believedthat the structural features of the transport carrier 108 can affectmicrowave energy absorption or reflection at the items 101 (FIG. 1) bycreating, modifying, or eliminating discontinuity in the immersion fluid110 (FIG. 1) proximate the items 101. For example, the lateral members188 a and 188 b (FIG. 7B) may create discontinuities in the immersionfluid 110 when microwave energy impacts the items 101 in the transportcarrier 108. The discontinuities may affect formation of a standing waveon or around the individual items 101, and thus affect a percentage ofabsorption or reflection of the microwave energy.

Based on the foregoing recognition, a target heating profile may beachieved in the processing system 100 of FIG. 1 by (1) selecting amaterial of construction for the individual cross members and/or lateralmembers 188 a and 188 b; and/or (2) adjusting a position of theindividual lateral members 188 a and 188 b. For example, FIG. 9 is aflowchart illustrating a process 200 of adjusting operation of aprocessing system 100 of FIG. 1 for sterilization or pasteurization inaccordance with embodiments of the disclosed technology. As shown inFIG. 9, the process 200 can include processing items (e.g., foodproducts) with a simulated composition configured to show observableeffects in response to heating under various temperature conditions atstage 202. For example, in certain embodiments, processing the items caninclude processing the items in the processing system 100 of FIG. 1, theprocessing system 100′ of FIG. 6, or other suitable processing systems.In other embodiments, processing the items can include heating the itemswith hot air, hot water, steam, or other suitable thermal media.

The process 200 can also include determining a heating pattern of theitems with the simulated composition at stage 204. In one embodiment,the heating pattern can be determined by monitoring a color profile ofthe simulated composition in a sectional, layered, or another suitablemanner. In other embodiments, the heating pattern can also be determinedby monitoring a profile in viscosity, gelation, and/or othercharacteristics of the simulated composition. The process 200 caninclude a decision stage 206 to determine if the determined heatingpattern is greater than a threshold.

In one embodiment, the threshold is a percentage of variation of theheating effects in the items. In other embodiments, the threshold caninclude other suitable values. In response to determining that thedetermined heating pattern is greater than the threshold, the process200 can include retaining the transport carrier configuration at stage210. In response to determining that the determined heating pattern isnot greater than the threshold, the process 200 can include adjustingthe transport carrier configuration at stage 208.

As discussed above, adjusting the transport carrier configuration caninclude at least one of (1) selecting a material of construction for theindividual cross members 182 (FIG. 7B) and/or lateral members 188 a and188 b (FIG. 7B); or (2) adjusting a position of the individual lateralmembers 188 a and 188 b. The process 200 then reverts to processingother items with simulated composition at stage 202. For example, in oneembodiment, selecting a material of construction can include selectingbetween a metal (or metal alloy) material and a plastic material for thecross members 182 and/or lateral members 188 a and 188 b. In anotherexample, selecting a material of construction can include selectingdifferent material for the individual cross members 182 (or lateralmembers 188 a and 188 b). In other example, selecting a material ofconstruction can include selecting between other suitable materials forat least one of the foregoing components of the transport carrier 108.

Even though the transport carrier 108 is described with reference toFIGS. 7A-8E as being configured to carry one row of items 101, in otherembodiments, the transport carrier 108 and the processing system 100 maybe configured to carry and process two, three, or any suitable number ofrows of items 101, respectively. For example, FIG. 10 shows across-sectional view of a processing system 100′ that has a transporthousing 123 configured to receive a transport carrier assembly 108′ thatincludes first and second transport carriers 108 a and 108 b coupledtogether by one or more sets of connectors 304. The first and secondtransport carriers 108 a and 108 b can each include a mesh 189configured to carry first and second rows of items 101 a and 101 b,respectively.

In one embodiment, the first and second transport carriers 108 a and 108b can be generally similar in structure and function. For example, eachof the first and second transport carriers 108 a and 108 b can begenerally similar to the transport carrier 108 described above withreference to FIGS. 7A-7C. In other embodiments, the first and secondtransport carriers 108 a and 108 b can include additional and/ordifferent components in other suitable configurations. In furtherembodiments, the first and second transport carriers 108 a and 108 b canhave different configurations adapted to carry items 101 of differentsizes, shapes, or other characteristics.

As shown in FIG. 10, in the illustrated embodiment, the processingsystem 100′ can include two parallel microwave assemblies 114 a and 114b each having two sets of microwave sources 116 a and 116 b. Themicrowave sources 116 a and 116 b are configured to deliver microwaveenergy 117 to the items 101 a and 101 b generally simultaneously via thecorresponding microwave windows 125 (FIG. 1) in the transport housing123. In other embodiments, the processing system 100′ can also includethree, four, or any suitable number of parallel sets of microwaveassemblies 114 (not shown) configured to process transport carrierassemblies 108′ having two, three, or any suitable number of transportcarriers 108.

As shown in FIG. 10, in the illustrated embodiment, the transportmechanism of the processing system 100′ can include a conveyor beltassembly 302 and one or more guide rails 129. In the illustratedembodiment, the conveyor belt assembly 302 includes a belt 306 driven bya motor (not shown) or other suitable types of actuators. The belt 306can include a plurality of contactors 308 that extend from a surface ofthe belt 306 toward the transport assembly 108′. The contactors 308 areconfigured to be in contact with the connectors 304 when the belt 306 ismoving in a direction along the transport housing 123. In operation, thecarrier transport assembly 108′ can have corners individually in contactwith the guide rail 129. As the belt 306 moves in a direction into thetransport housing 123, the contactors 308 can drive the carriertransport assembly 108′ into the transport housing 123 along the guiderails 129. Examples of the belt 306 and the contactors 308 are describedin more detail below with reference to FIGS. 11A and 11B. In otherembodiments, the transport mechanism can also include rollers as shownin FIG. 1, guide slots, and/or other suitable components.

FIG. 11A is a schematic top view of a transport carrier assembly 108′having two transport carriers suitable for the processing system of FIG.10. FIG. 11B is a schematic end view of the transport carrier assembly108′ along lines A-A. In FIGS. 11A and 11B, the mesh 189 is omitted forclarity. As shown in FIGS. 11A and 11B, the transport carrier assembly108′ include first and second transport carrier 108 a and 108 b coupledtogether in parallel using three sets of connectors 304. Each set ofconnectors 304 includes two connecting rods 304 a and 304 b, which canbe metallic, polymeric, or constructed with other suitable materialswith sufficient mechanical properties. Each of the connecting rods 304 aand 304 b can be coupled to the sides 181 of the first and secondtransport carriers 108 a and 108 b via welding, threads, fasteners(e.g., nuts and bolts), and/or other suitable mechanisms. In otherembodiments, the first and second transport carriers 108 a and 108 b canbe coupled with other suitable number of sets of connectors 304 eachhaving any suitable number of connectors.

Also shown in FIG. 11A, each of the connectors 304 can correspond to acontactor 308 of the conveyor belt 306. As discussed above, each of thecontactors 308 are configured to be in contact with the connecting rods304 b of the connectors 304. In operation, as the conveyor belt 306moves along the direction indicated by the arrow 310, each of thecontactors 308 can drive the transport carrier assembly 108′ along thesame direction via the individual connecting rods 304 b.

Several embodiments of the transport carrier assembly 108′ can reduce orprevent microwave energy spillage in the transport housing 123 (FIG.10). For example, during operation, the sides 181 (constructed from ametallic or other suitable material) of the first transport carriers 108a can reduce or prevent microwave energy 117 (FIG. 10) emitted from themicrowave sources 116 a (FIG. 10) to escape and spill over to the secondtransport carrier 108 b, and vice versa. Controlling the flow of theemitted microwave energy 117 in such a manner can result in a generallyuniform heating pattern and a generally consistent heating rate in theitems 101 a and 101 b carried in the first and second transport carriers108 a and 108 b, respectively.

FIG. 12 shows another transport carrier assembly 108′ that includesfirst, second, and third transport carriers 108 a-108 c coupled inparallel using sets of connectors 304. In FIG. 12, the transportcarriers 108 a-108 c can be generally similar to one another. In otherembodiments, at least one of the transport carriers 108 a-108 c can bedifferent in structure and/or function that other transport carriers 108a-108 c. In further embodiments, the transport carrier assembly 108′ canalso include four, or any other suitable number of carrier assemblies108 coupled in parallel via a suitable number of sets of connectors 304.

From the foregoing, it will be appreciated that specific embodiments ofthe disclosure have been described herein for purposes of illustration,but that various modifications may be made without deviating from thedisclosure. In addition, many of the elements of one embodiment may becombined with other embodiments in addition to or in lieu of theelements of the other embodiments. Accordingly, the technology is notlimited except as by the appended claims.

We claim:
 1. An apparatus for sterilization or pasteurizationcomprising: a heating section having a channel extending between a firstend and second and between a first side and a second side, the heatingsection having at least one window at either or both the first andsecond sides, the at least one window being transmissive to microwaveenergy, wherein the heating section includes an inlet and an outletconfigured to allow water to circulate in the channel; a transport unitwhich transports a plurality of items having water content through theheating section; at least one a microwave assembly coupled to the atleast one window of the heating section; a water supply for circulatingwater through the channel of the heating section and immersing theplurality of items in water while in the heating section and beingsubjected to microwave energy from the at least one microwave assembly;and one or both of a) at least one section in fluid communication withsaid heating section which is configured to contain water at anelevation above the heating section so as to apply a hydrostaticpressure to water in the heating section that is sufficient to preventthe water content of the items from causing steam explosion in the itemswhile the microwave energy from the at least one microwave assembly isapplied; and b) a plurality of transport carriers transportable by thetransport unit through the heating section with one or more of theplurality of items positioned in each of the plurality of transportcarriers, wherein each of the transport carriers includes side memberswhich are configured or constructed from a material to reduce themicrowave energy from the one or more microwave assemblies which escapesor spills over from the transport carrier when the microwave energy isapplied to the one or more of the plurality of items in the transportcarrier.
 2. The apparatus of claim 1 wherein the at least one microwaveassembly includes a microwave source and a microwave guide having afirst end coupled to the microwave source and a second end, wherein thesecond end is coupled to the at least one window of the heating section.3. The apparatus of claim 1 wherein the transport unit includes one ormore rollers proximate to one of the first or second sides of theheating section, the one or more rollers being configured to convey theplurality of items from the first end of the heating section, past thewindow, to the second end of the heating section.
 4. The apparatus ofclaim 1 wherein the at least one microwave assembly includes: amicrowave source; a microwave guide having a first end coupled to themicrowave source and a second end, wherein the second end is coupled tothe at least one window of the heating section, wherein the microwaveguide includes a plurality of sidewalls extending between the first andsecond ends of the microwave guide; and one or more microwave tuners,wherein the one or more microwave tuners are carried by one or more ofthe plurality of sidewalls of the microwave guide.
 5. The apparatus ofclaim 1 wherein the at least one window includes at least two windowswith a first window at the first side; of the heating section and asecond window opposite the first window at the second side of theheating section, the first and second windows being generally alignedwith each other; and wherein the microwave assembly includes: a firstmicrowave source and a first microwave guide having a first end coupledto the first microwave source and a second end coupled to the firstwindow; and a second microwave source and a second microwave guidehaving a first end coupled to the second microwave source and a secondend coupled to the second window.
 6. The apparatus of claim 1 whereinthe at least one window includes at least two windows with a firstwindow at the first side of the heating section and a second windowopposite the first window at the second side of the heating section;wherein the microwave assembly includes: a first microwave source and afirst microwave guide having a first end coupled to the first microwavesource and a second end coupled to the first window; and a secondmicrowave source and a second microwave guide having a first end coupledto the second microwave source and a second end coupled to the secondwindow; and wherein the transport unit includes one or more rollersproximate to one of the first or second side, the one or more rollersbeing configured to convey the plurality of items from the first end ofthe heating section, past the first and second windows, to the secondend of the heating section.
 7. The apparatus of claim 1 wherein the atleast one window includes at least two windows with a first window atthe first side of the heating section and a second window opposite thefirst window at a second side of the heating section; wherein themicrowave assembly includes: a first microwave source and a firstmicrowave guide having a first end coupled to the first microwave sourceand a second end coupled to the first window; and a second microwavesource and a second microwave guide having a first end coupled to thesecond microwave source and a second end coupled to the second window;and wherein the microwave assembly is configured to apply microwaveenergy to the plurality of items as each item of the plurality of itemsmoves from the first end of the heating section, past the first andsecond windows, to the second end of the heating section.
 8. Theapparatus of claim 1 wherein the at least one microwave assembly isconfigured to apply microwave energy sufficient to heat the items to atarget temperature, and further comprising a heater which maintains thewater circulating through the channel of the heating section at or abovethe target temperature, wherein the applied microwave energy and heatfrom the circulating water are sufficient to achieve sterilization orpasteurization of the plurality of items.
 9. The apparatus of claim 1wherein the at least one microwave assembly includes at least twomicrowave assemblies positioned on opposite sides of the heating sectionand simultaneously apply microwave energy to opposite sides of theplurality of items transported through the heating section.
 10. Theapparatus of claim 1 wherein the at least one section is a pre-heatingsection which contains water at a temperature that is lower than aheating temperature of water in the heating section and wherein theplurality of items are immersed in the water while in the pre-heatingsection.
 11. The apparatus of claim 10 further comprising a transportpath for transporting the plurality of items through the pre-heatingsection over a time period sufficient to homogenize a temperature of theplurality of items at the temperature of water in the pre-heatingsection.
 12. The apparatus of claim 1 wherein said at least one sectionfurther comprises a cooling section which contains water at atemperature that is lower than a heating temperature of water in theheating section and wherein the plurality of items are immersed in thewater while in the cooling section.
 13. The apparatus of claim 1 whereinthe at least one section is at an elevation that is at least four metersabove the heating section.
 14. The apparatus of claim 1 wherein the sidemembers of the transport carriers are constructed from metal or metalalloy.
 15. The apparatus of claim 1 wherein each of the plurality oftransport carriers comprises: a carrier base having a first end oppositea second end and a first side member opposite a second side member, thefirst and second side members extending between the first and secondends; the first and second side members being constructed from ametallic material and being perforated to allow circulation of heatedwater therethrough; one or more cross members carried by and extendingbetween the first and second side members of the carrier base; and atleast one lateral member extending between the first and second ends ofthe carrier base and which is securable to the one or more cross membersat a plurality of locations which are spaced from the first and secondside members by different distances, wherein said at least one lateralmember is configured to function as a plate in an internal volumedefined by the carrier base.
 16. The apparatus of claim 15 wherein thecarrier base, the cross member, and the lateral member respectively area first carrier base, a first cross member, and a first lateral memberforming a first subassembly; and wherein the transport carrier furtherincludes a second carrier base, a second cross member, and a secondlateral member generally similar to the first carrier base, the firstcross member, and the first lateral member, respectively, forming asecond subassembly; and a set of connectors coupling the first andsecond subassemblies arranged generally in parallel.